CFB boiler dynamic peak regulation system and method

Abstract

The invention belongs to the technical field of fluidized bed application, and discloses a CFB boiler dynamic peak shaving system and method.The CFB boiler dynamic peak shaving system comprises a hearth, a separator, a stocker, a tail flue and a deduster, a smoke outlet of the hearth is connected to the tail flue, the tail flue is connected to the deduster, the separator is connected between an outlet of the hearth and the tail flue, and the stocker is connected to the deduster. The bottom of the separator is connected to the hearth in a backflow mode, the tail flue is connected to the hearth in a backflow mode through the stocker, and the stocker is used for controlling the bed material amount entering the hearth, so that rapid lifting load peak regulation of the unit is completed. The amount of the bed material entering the hearth is controlled through the stocker, so that rapid lifting load peak regulation of the unit is completed; the flue gas valve is used for controlling the flow of tail flue gas sent out of the air preheater, so that the temperature of the cold end of the air preheater is increased, the problems of blockage and corrosion are effectively solved, and the operation stability and economical efficiency of the whole system are enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluidized bed application, and in particular relates to a CFB boiler dynamic peak regulation system and method. Background Art

[0002] Circulating fluidized bed boilers (CFB) play an indispensable role in modern power systems due to their excellent fuel adaptability, low pollutant emissions and good peak-shaving performance. However, with the rapid development of renewable energy and the increasing demand for peak-shaving capacity of power grids, the rapid load-changing capability of CFB boiler units has become the focus of technological development. Traditional CFB boiler designs often have difficulty meeting demand due to large system inertia and slow response speed when dealing with rapid changes in power grid loads.

[0003] In order to improve the rapid load change capability of CFB boilers, researchers have explored a variety of technical solutions. Such as optimizing combustion adjustment and control, air distribution optimization control, intelligent control system design, boiler water dynamics maintenance and utilizing CFB boiler energy storage system. Among them, high-temperature adiabatic compressed air energy storage system, as a storage technology, can store energy when the power load is low and release it quickly at the peak, thereby improving the load response speed of the boiler. Although these technologies have made certain progress, they still face many challenges in practical applications. For example, the efficiency and cost-effectiveness of the energy storage system, as well as the optimal control strategy under different loads. In addition, the stability and safety of CFB boilers during rapid load changes also need further research and improvement. Therefore, developing new technologies to improve the rapid load change capability of CFB boiler units while ensuring the environmental protection and economy of operation is a technical problem that the current power industry needs to solve urgently. Summary of the invention

[0004] The purpose of the present invention is to provide a CFB boiler dynamic peak regulation system and method to solve the above-mentioned technical problems.

[0005] In order to solve the above technical problems, the specific technical solutions of a CFB boiler dynamic peak regulation system and method of the present invention are as follows: A CFB boiler dynamic peak-shaving system comprises a furnace, a separator, a accumulator, a tail flue and a dust collector, wherein the outlet of the furnace is connected to the tail flue, the tail flue is connected to the dust collector, a separator is connected between the outlet of the furnace and the tail flue, a bottom reflux of the separator is connected to the furnace, the tail flue is connected to the accumulator, the accumulator is connected to the furnace, and the amount of bed material entering the furnace is controlled by the accumulator to complete the rapid rise and fall of the unit load peak-shaving.

[0006] Furthermore, the furnace includes an air distribution device, a primary air chamber and a secondary air port, the primary air chamber is arranged at the bottom of the furnace, the air distribution device is arranged above the primary air chamber, air is introduced into the primary air chamber at the bottom of the furnace as a gasifying agent, and air is distributed through the air distribution device so that the bed material in the furnace reaches a fluidized state, and the secondary air port is arranged on the side of the furnace to supplement the air required for incomplete combustion.

[0007] Furthermore, the separator includes a flue gas inlet, a flue gas outlet, a material leg and a return pipe. The flue gas inlet is arranged on one side of the separator, the flue gas outlet is arranged above the separator, the flue gas inlet is connected to the outlet of the furnace, the flue gas outlet is connected to the tail flue, the material leg is arranged at the bottom of the separator, incompletely burned bed material is deposited in the material leg, the bottom of the material leg is connected to the return pipe, and the return pipe is connected to the furnace for recovering incompletely burned bed material.

[0008] Furthermore, an economizer and an air preheater are provided in the tail flue, the flue gas outlet of the separator is connected to the inlet of the economizer, the outlet of the economizer is connected to the inlet of the air preheater, and the inlet of the air preheater is connected to the accumulator.

[0009] Furthermore, the accumulator includes a accumulator air chamber, an air distribution plate, a accumulator slag discharge pipe, a feed valve and a feed pipe, the accumulator air chamber is arranged at the bottom of the accumulator, the air distribution plate is arranged above the accumulator air chamber, the feed pipe is arranged at one side of the accumulator and connected to the primary air chamber of the furnace, the feed valve is arranged on the feed pipe for controlling the flow of the feed pipe, and the accumulator slag discharge pipe is arranged at one side of the accumulator for slag discharge.

[0010] Furthermore, the outer shell of the accumulator is made of steel plate and lined with insulating material and wear-resistant refractory material, and the outside of the outer shell is wrapped with refractory insulation bricks, insulation bricks or insulation blocks for insulation of the bed material.

[0011] Furthermore, the angle between the conveying pipe and the horizontal ground is 10-20 degrees, and the solid particles can enter the storage container through the conveying pipe by gravity.

[0012] Furthermore, a smoke valve is connected between the accumulator and the tail flue, the inlet of the smoke valve is connected to the outlet of the air preheater, and the outlet of the smoke valve is connected to the accumulator air chamber of the accumulator; the smoke valve is an electronic valve or a pneumatic valve, and the smoke valve is adjusted by wired communication or wireless communication.

[0013] Furthermore, the feed valve is an electronic valve or a pneumatic valve, which is adjusted by wired communication or wireless communication. The adjustment gear of the feed valve is set to 25%, 50%, 75% and 100%, corresponding to one quarter opening, half opening, three quarters opening and fully open state respectively.

[0014] The present invention also discloses a CFB boiler dynamic peak-shaving method of the CFB boiler dynamic peak-shaving system, comprising the following steps: When the load needs to be reduced quickly, the feed valve is opened to discharge part of the high-temperature bed material in the furnace. The feed pipe is at an angle of 15° to the horizontal ground. Solid particles enter the accumulator through the feed pipe by gravity to reduce the bed material concentration in the furnace, thereby reducing the thermal load of the boiler and storing the bed material in the accumulator with heat preservation performance. When the load needs to be increased quickly, the flue gas valve is opened to allow low-temperature flue gas to enter from the air distribution plate at the bottom of the accumulator. After the flue gas absorbs heat from the bed material in the accumulator, the feed valve is opened to send the flue gas into the furnace for flue gas recirculation. At the same time, the bed material in the accumulator that has been fluidized by the flue gas is returned to the furnace through the feed pipe, thereby increasing the bed material concentration in the boiler.

[0015] The CFB boiler dynamic peak-shaving system and method of the present invention has the following advantages: ① Due to the use of a accumulator, the dynamic peak-shaving capacity is increased, the equipment is simple, and the structure is compact; ② The amount of bed material entering the furnace is controlled by the accumulator to complete the rapid lifting and lowering of the unit load peak-shaving; ③ By using a flue gas valve to control the tail flue gas flow rate sent out of the air preheater, not only the temperature of the cold end of the air preheater is increased, the blockage and corrosion problems are effectively reduced, and the operation stability and economy of the entire system are enhanced. ④ The tail flue is used to burn and recover the flue gas heat, reduce the exhaust heat loss, and improve the thermal efficiency of the boiler.

[0016] In summary, the present invention improves the dynamic throughput and response speed of the CFB boiler through system design and control strategy, better ensures the stability and safety during load variation, enhances its peak load regulation capability in modern power systems, and meets the requirements of environmental protection emissions, with higher economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the CFB boiler dynamic peak-shaving system of the present invention; Explanation of the markings in the figure: 1. furnace; 2. return pipe; 3. air distribution device; 4. primary air chamber; 5. separator; 6. material leg; 7. feed valve; 8. accumulator; 9. air distribution plate; 10. accumulator air chamber; 11. accumulator slag discharge pipe; 12. flue gas inlet; 13. flue gas outlet; 14. economizer; 15. air preheater; 16. dust collector; 17. tail flue; 18. flue gas valve; 19. secondary air outlet; 20. return valve; 21. feed pipe. DETAILED DESCRIPTION

[0018] In order to better understand the purpose, structure and function of the present invention, a CFB boiler dynamic peak regulation system and method of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0019] like Figure 1 As shown, a CFB boiler dynamic peak-shaving system of the present invention includes a furnace 1, a separator 5, a accumulator 8, a tail flue 17 and a dust collector 16. The outlet of the furnace 1 is connected to the tail flue 17, and the tail flue 17 is connected to the dust collector 16. The dust collector 16 is used for dust removal of the tail flue gas. A separator 5 is connected between the outlet of the furnace 1 and the tail flue 17. The bottom reflux of the separator 5 is connected to the furnace 1. The separator 5 is used to separate the bed material and gas after combustion, and recycle the bottom bed material. The tail flue 17 is connected to the accumulator 8, and the accumulator 8 is connected to the furnace 1. The amount of bed material entering the furnace is controlled by the accumulator 8 to complete the rapid rise and fall of the unit load peak-shaving.

[0020] The furnace 1 includes an air distribution device 3, a primary air chamber 4 and secondary air ports 19. The primary air chamber 4 is arranged at the bottom of the furnace 1, and the air distribution device 3 is arranged above the primary air chamber 4. Air is introduced into the primary air chamber 4 at the bottom of the furnace 1 as a gasifying agent, and air is distributed through the air distribution device 3 so that the bed material in the furnace 1 reaches a fluidized state. A plurality of secondary air ports 19 are arranged on the side of the furnace 1 to supplement the air required for incomplete combustion.

[0021] The separator 5 includes a flue gas inlet 12, a flue gas outlet 13, a feed leg 6 and a return pipe 2. The flue gas inlet 12 is arranged on one side of the separator 5, and the flue gas outlet 13 is arranged above the separator 5. The flue gas inlet 12 is connected to the flue gas outlet of the furnace 1, and the flue gas outlet 13 is connected to the tail flue 17. The feed leg 6 is arranged at the bottom of the separator 5, and the incompletely burned bed material is deposited in the feed leg 6. The bottom of the feed leg 6 is connected to the return pipe 2, and the return pipe 2 is connected to the furnace 1 for recovering the incompletely burned bed material.

[0022] An economizer 14 and an air preheater 15 are provided inside the tail flue 17 . The flue gas outlet 13 of the separator 5 is connected to the inlet of the economizer 14 , the outlet of the economizer 14 is connected to the inlet of the air preheater 15 , and the outlet of the air preheater 15 is connected to the accumulator 8 .

[0023] The accumulator 8 includes an accumulator air chamber 10, an air distribution plate 9, an accumulator slag discharge pipe 11, a feeding valve 7, and a feeding pipe 21. The accumulator air chamber 10 is arranged at the bottom of the accumulator 8, the air distribution plate 9 is arranged above the accumulator air chamber 10, the feeding pipe 21 is arranged at one side of the accumulator 8 and connected to the primary air chamber 4 of the furnace 1, and the feeding valve 7 is arranged on the feeding pipe 21 to control the flow of the feeding pipe 21. The accumulator slag discharge pipe 11 is arranged at one side of the accumulator 8 for slag discharge.

[0024] The outer shell of the accumulator 8 is made of steel plate and lined with heat-insulating material and wear-resistant refractory material. The outer shell is wrapped with refractory insulation bricks, insulation bricks or insulation blocks for heat preservation of bed materials.

[0025] The angle between the conveying pipe 21 and the horizontal ground is 10-20°, preferably 15°, and the solid particles can enter the storage container 8 through the conveying pipe 21 by gravity.

[0026] In order to facilitate the control of the tail smoke flow rate entering the accumulator 8, a smoke valve 18 is also connected between the accumulator 8 and the tail flue 17. Specifically, the inlet of the smoke valve 18 is connected to the outlet of the air preheater 15, and the outlet of the smoke valve 18 is connected to the accumulator air chamber 10 of the accumulator 8; the air distribution plate 9 and the accumulator air chamber 10 can pass smoke from the tail flue 17 through the smoke valve 18, thereby reducing the heat loss of smoke exhaust. In order to facilitate the operation of the staff during adjustment, the smoke valve 18 is an electronic valve or a pneumatic valve, and the smoke valve 18 is adjusted specifically by wired communication or wireless communication.

[0027] In order to facilitate the staff's adjustment operation, the feed valve 7 is an electronic valve or a pneumatic valve, and the feed valve 7 is adjusted by wired communication or wireless communication. The adjustment gear of the feed valve 7 is accurately set to 25%, 50%, 75% and 100%, corresponding to one-quarter opening, half-open state, three-quarter opening and full-open state respectively, so as to achieve fine control of the bed material delivery amount.

[0028] A CFB boiler dynamic peak regulation method of the present invention comprises the following steps: When it is necessary to reduce the load quickly, open the feed valve 7 to discharge part of the high-temperature bed material in the furnace 1. The feed pipe 21 forms an angle of 15° with the horizontal ground. Solid particles can enter the storage container 8 through the feed pipe 21 by gravity to reduce the bed material concentration in the furnace. The bed material is stored in the storage container 8 with thermal insulation performance, thereby reducing the thermal load of the boiler.

[0029] When it is necessary to increase the load quickly, open the flue gas valve 18, and let the low-temperature flue gas enter from the accumulator wind chamber 10 at the bottom of the accumulator 8, pass through the air distribution plate 9, and after the flue gas absorbs heat from the bed material in the accumulator 8, open the feed valve 7 to send the flue gas into the furnace for flue gas recirculation. At the same time, the bed material in the accumulator 8 fluidized by the flue gas is returned to the furnace 1 through the feed pipe 21, so that the bed material concentration in the furnace 1 is increased, the heat exchange is enhanced, and the load change rate is increased.

[0030] The flue gas temperature entering the accumulator 8 is 110~140℃, the bed material of the accumulator 8 is mostly bottom ash, a small amount of unburned coal and fly ash, with a particle size of 50~500μm, and the bed material temperature is 800~1000℃. The fluidization wind speed in the accumulator 8 is 3~4m / s to ensure that it is in a bubbling bed state.

[0031] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A CFB boiler dynamic peak load regulation system, comprising a furnace (1), a separator (5), a hopper (8), a tail flue (17) and a dust collector (16), wherein the outlet of the furnace (1) is connected to the tail flue (17), the tail flue (17) is connected to the dust collector (16), a separator (5) is connected between the outlet of the furnace (1) and the tail flue (17), and the bottom of the separator (5) is refluxed and connected to the furnace (1), characterized in that: The tail flue (17) is connected to a accumulator (8), and the accumulator (8) is connected to the furnace (1). The amount of bed material entering the furnace is controlled by the accumulator (8) to achieve rapid load peaking of the unit.

2. The CFB boiler dynamic peak load regulation system according to claim 1, characterized in that: The furnace (1) comprises an air distribution device (3), a primary air chamber (4) and a secondary air port (19); the primary air chamber (4) is arranged at the bottom of the furnace (1); the air distribution device (3) is arranged above the primary air chamber (4); air is introduced into the primary air chamber (4) at the bottom of the furnace (1) as a gasifying agent, and air is distributed through the air distribution device (3) so that the bed material in the furnace (1) reaches a fluidized state; the secondary air port (19) is arranged on the side of the furnace (1) and is used to supplement the air required for incomplete combustion.

3. The CFB boiler dynamic peak load regulation system according to claim 1, characterized in that: The separator (5) comprises a flue gas inlet (12), a flue gas outlet (13), a feed leg (6) and a return pipe (2); the flue gas inlet (12) is arranged at one side of the separator (5); the flue gas outlet (13) is arranged above the separator (5); the flue gas inlet (12) is connected to the outlet of the furnace (1); the flue gas outlet (13) is connected to the tail flue (17); the feed leg (6) is arranged at the bottom of the separator (5); incompletely burned bed material is deposited in the feed leg (6); the bottom of the feed leg (6) is connected to the return pipe (2); the return pipe (2) is connected to the furnace (1) and is used to recover incompletely burned bed material.

4. The CFB boiler dynamic peak load regulation system according to claim 1, characterized in that: The tail flue (17) has an economizer (14) and an air preheater (15), the flue gas outlet (13) of the separator (5) is connected to the inlet of the economizer (14), the outlet of the economizer (14) is connected to the inlet of the air preheater (15), and the inlet of the air preheater (15) is connected to the accumulator (8).

5. The CFB boiler dynamic peak load regulation system according to claim 1, characterized in that: The accumulator (8) comprises an accumulator air chamber (10), an air distribution plate (9), an accumulator slag discharge pipe (11), a feed valve (7) and a feed pipe (21), wherein the accumulator air chamber (10) is arranged at the bottom of the accumulator (8), the air distribution plate (9) is arranged above the accumulator air chamber (10), the feed pipe (21) is arranged at one side of the accumulator (8) and connected to the primary air chamber (4) of the furnace (1), the feed valve (7) is arranged on the feed pipe (21) and is used to control the flow of the feed pipe (21), and the accumulator slag discharge pipe (11) is arranged at one side of the accumulator (8) and is used to discharge slag.

6. The CFB boiler dynamic peak load regulation system according to claim 1, characterized in that: The outer shell of the accumulator (8) is made of steel plate and lined with heat-insulating material and wear-resistant refractory material. The outer shell is wrapped with refractory insulation bricks, insulation bricks or insulation blocks to keep the bed material warm.

7. The CFB boiler dynamic peak load regulation system according to claim 5, characterized in that: The angle between the conveying pipe (21) and the horizontal ground is 10-20 degrees, and the solid particles can enter the storage container (8) through the conveying pipe (21) by gravity.

8. The CFB boiler dynamic peak load regulation system according to claim 5, characterized in that: A smoke valve (18) is connected between the accumulator (8) and the tail flue (17); an inlet of the smoke valve (18) is communicated with an outlet of the air preheater (15); and an outlet of the smoke valve (18) is communicated with an accumulator air chamber (10) of the accumulator (8); the smoke valve (18) is an electronic valve or a pneumatic valve, and the smoke valve (18) is adjusted by wired communication or wireless communication.

9. The CFB boiler dynamic peak load regulation system according to claim 5, characterized in that: The material delivery valve (7) is an electronic valve or a pneumatic valve, and the material delivery valve (7) is adjusted by wired communication or wireless communication. The adjustment gear positions of the material delivery valve (7) are set to 25%, 50%, 75% and 100%, corresponding to a quarter opening, a half-open state, a three-quarter opening and a fully open state, respectively.

10. A CFB boiler dynamic peak-shaving method of the CFB boiler dynamic peak-shaving system according to any one of claims 1 to 9, characterized in that: The steps include: When it is necessary to reduce the load quickly, the feed valve (7) is opened to discharge part of the high-temperature bed material in the furnace (1), the feed pipe (21) forms an angle of 15° with the horizontal ground, and solid particles enter the storage container (8) through the feed pipe (21) by gravity to reduce the bed material concentration in the furnace, thereby reducing the thermal load of the boiler, and the bed material is stored in the storage container (8) with heat preservation performance; When it is necessary to quickly increase the load, the flue gas valve (18) is opened to allow low-temperature flue gas to enter through the air distribution plate (9) at the bottom of the accumulator (8). After the flue gas absorbs heat from the bed material in the accumulator (8), the feed valve (7) is opened to feed the flue gas into the furnace (1) for flue gas recirculation. At the same time, the bed material in the accumulator (8) fluidized by the flue gas is fed back into the furnace (1) through the feed pipe (21), thereby increasing the bed material concentration in the boiler.

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